Is SBEM fit for business?

Perhaps faced with the impending London property market meltdown post Brexit, I have recently noticed that lenders are beginning to ask for evidence of higher EPC scores for commercial buildings in order that their owners can borrow against them with less of risk to the lender (as of a couple or weeks ago Santander demanded a C or above).

Understandably many building owners reacting to the tightening of lending criteria are looking for the cheapest solution to getting their building up to spec in order that they can borrow against them, and here in is the point of this article.

Due to generic design flaws, SBEM allows for legitimate site data to be massaged into an EPC that has the potential for ratings to differ significantly depending on the assessor behind the modelling.

are the use of Commercial EPCs as a tool for bench marking building valuation open to greater exploitation in the face of an increasingly strained economic business environment?

Here are some of my observations when using SBEM methodology for generating EPCs.

1. Same building, different result.

Depending upon how you group/define your zones, position you windows and orientate the building the calculated results can be massively varied. If you are on a mission to hit a specific score (e.g. a ‘D’ to enable full Solar PV Tariff allowance) then this can be good news for the building owner.
It is therefore possible to work with the same completely legitimate site data to produce an EPC with a score that reflects more on how well the client treated you, than how energy efficient the building is.

Example 1. Moving a window a few cm on the model can nudge a borderline EPC rating into a higher (or lower) category

2. Building fabric is far too open to interpretation and hardly ever questioned during audit

Why have several options for defining the composition of wall if they all lead to the same conclusive U value? What is the point in clogging up the interface with meaningless descriptive when they will never be used? Why chance a request for evidence during audit by stipulating that a building was signed off under a specific set of building regulations when in 99% of cases the evidence simply does not exist. Surely it is far easier (and safer) to define an envelope as a solid brick wall, no date, no insulation, than a 20cm 1974.5 rendered brick wall with 5cm of internal insulation with a recent addition of 83.56% coverage of weatherboarding? NCM should stop pretending that that the enormous options for fabric definition matter. They don’t, they never will and all they do is provide more opportunity for incorrect building interpretation.

Example 2. Taking the ‘best in class’ example of walls, ceilings, roofs and floors and applying the values to the entire building will artificially raise the rating of the building, especially if it has been recently extended or partially upgraded

I suggest the definition of building fabric is stripped back to basics and completely scraps the Inferred or simple options for classification.

3. HVAC settings are too ambiguous, out of date and difficult to populate with modern system specifications

Again, far too many options that most assessors will completely ignore or incorrectly assign. Do you really think the owner of the building has clue whether the air heating system is fixed or variable flow ? How about tidying up the efficient requirements and bringing them in line with the way MODERN equipment is rated. Square peg round hole – and you complain that Assessors over-use default values.

Example 3. Turning off off HVAC for poorly insulated zones, for example large, gas powered air heaters in solid brick factories with single skin asbestos roofs. This will often have the effect of considerably improving the rating of the building, especially if there are insulated offices included in the overall model

Extract ventilation rates is a pet hate and audit trap that demands population yet bears no resemblance to reality. Obsessing about extract ventilation forces the assessor to values in WC and Tea Making areas even if there isn’t a fan in sight. It’s often just easier to put it in than have to explain to the auditor why it isn’t there. If extract is such a big deal then SBEM should have the intelligence to assume that it’s there and calculate it automatically based upon zone height, activity and age of building, rather than the current system which as mentioned earlier appears to be wired as an audit trap for unsuspecting assessors.

4. Hot Water Systems don’t allow for modern insulation types

Sort out the insulation definitions please. This isn’t the 1980s there insulation meant a copper tank wrapped in fibreglass. Now we have a thing called ceramic or metallic insulation which is only a couple of mm thick and is found INSIDE that vessel which by virtue of being INSIDE a sealed tank can not be directly observed. How about reflecting (pardon the pun) this in your definition options?

Example 4. Buildings often have more than one HW system and often not all of the building can be accessed to determine which system is applied in specific zones. Needless to say, instant HW systems will often contribute towards a higher rating than an individual dedicated HW heater

5. Glazing

If an assessor diligently measured every single window and lovingly noted each windows individual composition, frame faction, shading and positioning, the income of the assessor would probably fall below minimum wage as it would take several days to complete each site assessment. SBEM recognises this and instead allows the assessor to work on overall percentages. However, this also renders the options to submit detailed glazing info as pointless. Either make it compulsory or don’t. In fact, this is the whole underlying issue with SBEM. It gives you a choice to perform a ridiculously thorough assessment and build a highly detailed thermal model, or in the interest of personal economics and common sense, limit your time on site to capture essential information only.

Under the SBEM umbrella, differing approaches to site survey whilst all legitimate, will return different EPC ratings depending upon how the modeller interprets that site data.

Sometimes quite substantial differences are observed.

6. Display lighting??

This is simply ridiculous. Enforcing the inclusion display lighting in an entrance zone? Why SBEM? Why?

Asking for highly technical lighting specifications is another example of the over complication of what should be a simple classification.

Gaming the system and passing audit is not rocket science, should you be so inclined (or motivated..)

It goes without saying that based upon the information within this article I do not in any way suggest that an assessors (self included) should manipulate or alter their field date to achieve a score that misrepresents the building in any way.

Should you find this article interesting, please feel free to PM me to discuss further.